The present invention relates to an injector for injecting a flexible intraocular implant, and in particular it relates to a piston for such an injector.
Intraocular implants are vision-correction systems constituted by an optical portion and by a haptic portion, the haptic portion serving to hold the implant in the eye in such a manner that its optical portion presents an axis which coincides with the axis of the eye of the patient fitted with the implant. The implant is usually placed in the capsular bag of the eye once the natural lens has been removed, but it can also be put in place in the anterior chamber or in the posterior chamber of the eye of the patient.
In order to reduce the size of the incision required for putting the implant into place inside the eye, intraocular implants have been developed having an optical portion that is flexible and made of silicone or hydrophilic or hydrophobic acrylic materials. With such implants, it is possible to fold or to roll up the optical portion of the implant before inserting it into the eye, thereby enabling the total size of the implant to be reduced while it is being inserted into the eye.
The haptic portion of the implant has a purely mechanical function as explained above, and it can be presented in various ways. In some cases, the haptic portion is constituted by two haptic elements also made of a flexible material, which can therefore be rolled up or folded together with the optical portion. In other cases, the haptic portion can be constituted by two haptic branches presenting regular curvature and made of an intrinsically rigid material such as polymethylmethacrylate (PMMA), and having flexibility properties resulting from the small transverse size of the branches.
In order to assist the surgeon while the implant is being put into place in the eye, devices called intraocular-implant injectors have been developed which fulfill the dual function of rolling up or folding the implant and of inserting the folded implant into the eye by means of a hollow tube inserted through the incision made in the cornea of the eye.